The present invention relates to a semiconductor package with metal pads replacing of the outer leads, such as QFN, SON package structure, and especially to a semiconductor package with metal pads that there is an interval between a metal pad and corresponding cutting surface for avoiding the formation of a sharp edge.
Conventional semiconductor device includes a die protected from injury of the hostile environment by using a package body to seal, and a lead frame (leads) for electrically connecting the die of the semiconductor package to a printed circuit board, such as Quad Flat Package, QFP with outer leads around the package body or Small Outline Package, SOP with outer leads at the both sides of the package body.
With small size of the semiconductor package, a semiconductor package with metal pads replacing of outer leads brought up from U.S. Pat. No. 6,143,981 xe2x80x9cPlastic Integrated Circuit Package And Method And Lead frame For Making The Packagexe2x80x9d may decrease the surface footprint. FIG. 1 and FIG. 3 are cross sectional view and side view of a semiconductor package 100 respectively. As shown in FIG. 2, a lead frame 170 is going to encapsulate the semiconductor package 100. The lead frame 170 has a plurality of frames 171, each frame 171 connects a die pad 130 and a plurality of leads 140 facing the die pad 130. After sticking a die 110 on the die pad 130, electrically connect the bonding pads of the die 110 to topside surfaces of the leads 140 with bonding wires. Then there is a package body 120 (or called encapsulant material) formed by molding, injection and baking to seal the die 110, bonding wires 150, and the topside surfaces 141 of the leads 140, but to expose the downside surfaces 142 (metal pads) of the leads 140 in which use of outer electrical connection of the semiconductor package. After electroplating the downside surfaces 142 of leads 140, a plurality of whole semiconductor packages 100, such as Quad Flat Non-leaded package, QFN or Small Outline Non-leaded package, SON, may be gained through cutting the leads 140 along the package body 120. However, as shown in FIG. 3, the cutting surfaces 143 of leads 140 on the lateral surface of package body 120 are adjacent to downside brim of package body 120 and connect with the downside surface 142 of the corresponding leads 140 (as shown in FIG. 1). It is easy to form a sharp edge at the brim 144 of downside surface 142 of leads 140 so that it may affect the coplanarity of the downside surface 142 of leads 140 and results in a surface-mounting fail with a printed circuit board.
The first object of the present invention is to provide a semiconductor package with metal pads, each metal pad is formed by partial downside surface of the corresponding lead, a plurality of metal pads are formed on a same plane. In order to avoid forming the cutting sharp edge at the brim of metal pads during cutting leads to affect the surface mounting and simultaneously enhance the fixing stability of the leads to the package body, an interval is formed between the cutting surface of the lead and the plane of forming metal pads by means of gap-etching or bend-stamping.
The second object of the present invention is to provide a leadframe for non-leaded semiconductor package. By using that all the cutting portions of the leads are higher than the metal pads on the downside surface of lead, the downside surfaces of leads between metal pads and cutting portions can be covered by the package body, therefore the cutting sharp edges may be avoided forming at the brims of metal pads.
According to the present invention, a semiconductor package with metal pads mainly comprises a die, a plurality of leads, a plurality of electrical connecting devices and a package body. The die has a topside surface with a plurality of bonding pads and a downside surface opposite to the topside surface. Each lead has a topside surface, a downside surface and a cutting surface. The electrical connecting devices, such as bonding wires, are to electrically connect the bonding pads of the die to the topside surface of the corresponding lead. The package body seals the topside surface of the die, the electrical connecting devices and the topside surfaces of the leads, but exposes the partial downside surfaces of leads to form the metal pads. There is an interval between the cutting surfaces and a plane that the metal pads are formed on for avoiding forming a sharp edge at the brim of the metal pad.